1. Field of the Invention
One disclosed aspect of the embodiments relates to an image pickup apparatus.
2. Description of the Related Art
In recent years, a development of an image pickup apparatus has been remarkable. An apparatus configured to perform a focus detection in a pupil division system by using an image sensor in which micro lenses are formed on respective pixels of the image pickup apparatus is disclosed (Japanese Patent Laid-Open No. 2003-244712, which will be hereinafter referred to as Patent Document 1).
According to Patent Document 1, the image pickup apparatus is arranged on an expected imaging surface of a taking lens. A single pixel of the image pickup apparatus is constituted by a light receiving portion A and a light receiving portion B, and the respective light receiving portions are arranged so as to be substantially conjugated with a pupil of the taking lens by the micro lenses of the image pickup apparatus formed on a taking lens side.
At the time of the focus detection, signals are independently read out from each of photoelectric conversion units A and B of a plurality of pixels, and two images based on light beams that have transmitted at mutually different locations of the pupil of the taking lens are accordingly generated. Image information can be obtained by adding the two photoelectric conversion units A and B to each other.
However, according to Patent Document 1, since the signals of the photoelectric conversion units A and B are respectively independently read out, transfer transistors configured to perform the readout corresponding to the number of pupil divisions and drive lines for driving switches thereof are prepared. When the numbers of these transfer transistors and drive lines are increased, short-circuit between the drive lines may more easily be caused. More consideration is to be taken with regard to an image quality in a case where these drive lines are mutually short-circuited. Alternatively, in a case where the drive lines are laid out while securing a distance between the drive lines so as not to cause such short-circuit, it is difficult to achieve a miniaturization in a chip area.